Originally Posted by flashhole
The link was for 300/221 brass, that's a 221 Fireball case opened up to accept a 30 cal bullet ... also known as the 300 Whisper.
It is not too difficult to reform 223 to 221 Fireball but some brass will require a lot more work than others. Military brass can be significantly thicker in the web making neck turning mandatory. I like to use mil brass for that exact reason. Commercial brass from Winchester or Remington does not require neck turning to make a usable re-form.
I've never owned anything in .221 Fireball for starters, but I do shoot several .223's and a couple .222's. One of my .222's has a chamber with a .246 neck and is of national match quality. A few years back .222 brass was hard to come by, and I simply built brass out of remington .223 brass I had. It formed pretty easy with a borrowed bushing die (I used a .258 bushing to rough it in, and rough trim the length). Then I ran the cases thru a Forster .222 full length die to set the actual headspace (this was harder than using the bushing die). After that I turned the necks for about .0025" clearence in the chamber, and fireformed tham. Near perfect cases everytime. I think you should be able to do a .221 even easier by first running the cases thru a .222 die, and trimming them about .06" long for a .221. Then run them tru the .221 die. You'll get to neck turn them to fit the chamber neck I.D., so you may well come out ahead. BUT! Don't use military brass or even Federal brass for this. It's too hard and heavy for this kind of work. And it's a good idea to anneal the case necks all the way into the shoulder before you even start (your gonna cut that part off anyway)